#include <stdio.h>

int main()
{
	int x, y;
	scanf("%d",&x);
	if(x < 1)
	  y = x;
	  else if(x >= 1 && x <10)
	   y = 2*x -1;
	   else
	     y = 3*x -11;
	printf("%d",y);
	
	return 0;
}
